How Trees Talk to Each Other

December 28, 2016

About 20 years ago we logged our hunting property. We chose a local logger who was as sustainably-minded as we were. Although he selectively took out the big trees sought after by commercial enterprise, he also left “Mother trees” to help regenerate our forest. I understood the basic concept of the Mother trees, but it wasn’t until recently that I understood the science behind it. This Ted talk by Forest Ecologist Suzanne Simard entitled “How trees talk to each other” has been a big help.

Trees are the foundation of forests. Together they provide a sort of intelligence that allows the forest to communicate through a system of biological pathways connecting the trees. These biological pathways are a system of “below-ground fungal networks (mycorrhiza) that connects the trees and enables underground inter-tree communication and interaction.”

Professor Simard has been doing research for the 30+ years which proves that trees talk to each other. Her early experiments between Paper Birch (Betula papyrifera) and Douglas Fir (Pseudotsuga menziesii) show that they share carbon between themselves and that the back and forth trading of the carbon depends upon the season and the needs of the two species. Later research shows that they also communicate in the language of nitrogen and phosphorus, water, defense signals, allele chemicals and hormones – all of which are considered necessary for sustained growth.

Scientists have known for some time that the system of mycorrhiza is involved with the trade of carbon through mycelium. Because mycelium coats every soil particle, it enables the connection between the individual plants in the forest. Like a network, the system of mycorrhiza has links and nodes and hubs. The hubs in the case of the forest are the “Mother trees” which scientists now know send their excess carbon through the mycorrhizal network to their understory seedlings. They also will reduce their own root competition to make it easier for their seedlings. Or, if they are injured or dying, will send their carbon along with defense signals to strengthen the seedlings resilience to future stressors.

Professor Simard concludes her presentation by stressing less cutting of “Mother trees,” but does not suggest no cutting. She also suggests that local involvement in forestry practices is just as important as a sustainable and biodiversified focus in regeneration of tree species.

We shall forever be grateful for our logger’s thoughtful approach to logging.